This paper presents a systematic investigation of microstructure, mechanical properties and residual stress distribution of explosion-welded Al/steel plates. It was found that vortexes resulted from the trapped jetting were surrounded by highly deformed bulk materials and Fe–Al intermetallics. The microstructure-mechanical property relationship in individual phases was established using nanoindentation tests, e.g. FeAl + FeAl2 and FeAl3 having the hardness of 16.2 GPa and 11.4 GPa, respectively. The Al/steel interface showed higher microhardness values (200–300 HV0.1). The internal stresses were evaluated by a contour method, and the tensile stresses concentrated at the Al/steel interface, reaching to 170 MPa and 160 MPa in the longitudinal and transverse directions, respectively. Smoothed particles hydrodynamics (SPH) methods was used to simulate the formation of wave boundary, vortex zone, as well as the jet moving ahead of the collision point during the high-velocity oblique process. A good agreement was observed between the simulation and experiment, especially the formation of intermetallic compounds at interfacial regions and the evolution of residual stress.